How to Use the ACOG Scope

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The Advanced Combat Optical Gunsight (ACOG) is a tactical scope developed by Trijicon. The scope is designed for use with tactical weapons in a wide variety of lighting conditions. ACOG scopes feature illuminated reticles operating without batteries. The scope combines fiber optics that react to ambient light, providing optimum reticle illumination regardless of light conditions, with Hydrogen-3 (a self-luminous radioactive material also known as tritium) that illuminates the aiming point even in total darkness.

Items you will need

  • ACOG Scope

  • Weapon equipped with flat-top scope mounting rail

  • 1/4 inch flat-head screwdriver

Step 1

Inspect the ACOG by bringing your scope into a dark room and allowing your eyes to adjust to the darkness for approximately one to two minutes (the reticle is difficult to see until your eyes adjust). Look through the scope. If the ACOG is functioning properly you will see the illuminated reticle.

Step 2

Install the ACOG scope by loosening the knobs at the base of the its clamp assembly. Place the scope on the flat-top rail, the studs aligned within the rail grooves. Turn the knobs until finger-tight and add an additional quarter turn using a flat-head screwdriver (a 1/4 inch head screwdriver will suffice, however you do have some latitude with the screwdriver size as long as it works).

Step 3

Zero the ACOG by determining the rifle's point of impact in relation to the center of the reticle, either by using a boresighter (recommended) or by using live ammunition at a target range. Adjust the scope axis accordingly until the point of impact matches the center of the reticle. The ACOG adjustment increments are measured at a 1/4 inch per click at 100 meters. Therefore to move the reticle center one inch at a range of 100 meters requires four clicks in the desired direction. The reticle adjusters are located on the top of the scope and on the right side.

Step 4

Clean your ACOG by using the brush side of the "lenspen" (the cleaning device included with your ACOG) to remove any dirt or other material from the lens. Once clear of foreign material, use the pen's felt cleaner to finish clearing the lens.


  • The ACOG scope contains radioactive material and should only be repaired by the manufacturer. If you suspect your ACOG scope of leaking or being broken, place the scope in a sealed plastic bag, wash your hands thoroughly with soap and water and contact the manufacturer for handling instructions.


  • If you encounter resistance while zeroing in your ACOG, do not force the reticle adjusters. This can damage the internal prism assembly. In this event contact the manufacturer for further instructions.
  • If the ACOG doesn't work, contact the manufacturer for further instructions.
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